Quality expectations and tolerance limits of trial master files (TMF) - Developing a risk-based approach for quality assessments of TMFs.

This article addresses the question of when a trial master file (TMF) can be considered sufficiently accurate and complete: What attributes does the TMF need to have so that a clinical trial can be adequately reconstructed from documented data and procedures? Clinical trial sponsors face significant challenges in assembling the TMF, especially when dealing with large, international, multicenter studies; despite all newly introduced archiving techniques it is becoming more and more difficult to ensure that the TMF is complete. This is directly reflected in the number of inspection findings reported and published by the EMA in 2014. Based on quality risk management principles in clinical trials the authors defined the quality expectations for the different document types in a TMF and furthermore defined tolerance limits for missing documents. This publication provides guidance on what type of documents and processes are most important, and in consequence, indicates on which documents and processes trial team staff should focus in order to achieve a high-quality TMF. The members of this working group belong to the CQAG Group (Clinical Quality Assurance Germany) and are QA (quality assurance) experts (auditors or compliance functions) with long-term experience in the practical handling of TMFs.

Polyubiquitination of lysine-48 is an essential but indirect signal for MHC class I antigen processing.

Peptides presented on major histocompatibility complex (MHC) class I molecules are generated via cytosolic proteolysis. However, the nature of the endogenous peptide precursors and the intracellular processing steps preceding protein degradation remain poorly defined. Here, we assessed whether ubiquitination is an essential signal for proteasomal cleavage of antigen substrates in human cells. Conversion into antigenic peptides occurred in the absence of any detectable N-terminal ubiquitination of the model antigens, and did not require the presence of any of the four types, nor a minimum number of ubiquitinatable amino acids within the antigen substrate. However, the knockdown of ubiquitin, expression of a lysine 48 (K48) ubiquitin mutant, or inhibition of proteasome-associated deubiquitinases significantly impaired antigen presentation. The results presented here are consistent with a model in which the binding of the antigen substrate by an adaptor protein leads to its K48-polyubiquitination and the subsequent delivery of the antigen cargo for degradation by the 26S proteasome. Altogether, these findings show an important but indirect role of K48-polyubiquitination in preproteasomal antigen sampling.